1. Field of the Invention
The present invention relates to a test circuit for a test of a traffic signal in a multiplex equipment. By using this test circuit, the number of test cables is reduced and a working time for the cable connection can be shortened.
Multiplex equipment which multiplexes low speed signal groups, forms high speed signal groups, and transmits a multiplex signal, is used in a general asynchronous multiplex transmission system or in a synchronous multiplex transmission system wherein all the transmission system operates synchronously.
When multiplex equipment is installed or a failure occurs in the equipment, any failure of a low speed unit must be detected by the error test for the traffic signal. A reduction in the cost of a test cable and in the amount of testing time are required.
2. Description of the Related Art
In an error test for the traffic signal, in conventional multiplex equipment, many connecting cables are necessary, because the low speed units of one station must be connected in tandem. If the number of the low speed unit in N, then N-1 connection cables are necessary. For example, in the case when the low speed signal group is comprised of 63 channels and 2 Mb/s is multiplexed to form a high speed signal group of 140 Mb/s, 62 connection cables are necessary so the cable cost for test equipment increases.
Usually, the cables for the low speed units are connected manually, and accordingly, when many low speed units are connected, a large amount of time is required to connect and disconnect the many test cables. Particularly, when the failing units are detected, the labor time for testing increases, and the cost for the test also rises.